Production of aromatic hydrocarbons



Aug. 26, 1952 s. E. ROBINSON PRODUCTION OF AROMATIC HYDROCARBONS Filed Nov. 8, i948 2 SHEET'S-SHEET l A T TORNE y Patented Aug. 26, 1952 I'PRODUCTION oF ARoMA'rIo mRocAnBoNs i SamlRRobinson, Bartlesville, Okla., assigner t Phillips Petroleum Company, a corporation of y Delaware Application November 8, 1948, Serial No. 58,89?!A This invention relates to the production of aromatic hydrocarbons. `:In one aspect this invention relates tothe manufacture of light aromatic hydrocarbons together .with `relatively minor amounts of diolenic hydrocarbons and heavier aromatic hydrocarbons. In another aspect this invention relates to a two-stage process wherein a hydrocarbon gas is converted tolight aromatic hydrocarbons, such as benzene, toluene, Axylene and the like, `and to relatively minor amounts of diolen hydrocarbons and heavier aromatics.

Asis well known to the Workers in the art, hydrocarbons `may beiconverted into acetylene by 4a high temperature heat treatment, such aspassage through the .electric arc', e partial combustion at high temperatures,` or the like. Temperaturesin excessl'of 2000 E; are` necessary to obtaingood yields of acetylene, although some acetylene may be formedat much lower temperatures. `It is also well known that at an appropriate temperature, say in the range of about 1000 to 12.00 F.acetylene polymerizes rapidly to benzenefandother normally liquid aromatichydrocarbons. Therefore, it is possible t0 convert a gaseous hydrocarbon to normally liquid aromatic hydrocarbons by subjecting a gaseous hydrocarbon toa primary heat treatment, at. high temperature, in which acetylene is formed, and then subjecting the acetylene-containing gas product to a secondary heat treatment ata relatively low temperature, such as from 1000 to 1200 F. as already mentioned.` i

However, in the temperature range of 1000 to 1200 F., the contact time required for formation of economically feasible yields of light aromatic hydrocarbon product is s o long as to promote various side reactions, such as polymerization of acetylene product to form-high molecular weight cyclic hydrocarbons, and rehydrogenation of acetylene product to ethane. Under such conditions, high andeselective yeldsof light aromatic hydrocarbons are not obtained.` In the past, this has been the case even toa larger extent ,when operating at temperatures high?! than 1000, to 1200 F. due to concomitantly increased carbon and polymer formation, resulting Iin evenlower yieldsof desired product; f l i This invention is concerned with a'two-stage process `wherein a'cz'atylene product of Aan acetylene-'forming step is eonvertedtoflight aromatic hydrocarbon product in high and selectiveyield, at temperatures from 600 to 1000"F. abovethose ordinarily employed in the manufactureof aromatic hydrocarbons from acetylene, and wherein carbon and polymer formationisfsubstantially prevented. `1

, L4 Claims. (o1. aco-Mm An object of this `invention is to provide a proef ess for the manufacture of aromatic hydrocarbons.

Another object is to provide a process for the production of aromatic hydrocarbons from acetylene-containing stocks.

Another object is to utilize temperatures higher than heretofore in the manufacture of aromatic hydrocarbons from acetylene-containing gas.

Another object is to `provide a two-stagevprocess for the manufacture of aromatic hydrocarbons wherein an acetylene-containing gas proci-V uct is formed in a iirst s tagegand is thenconverted in a second stage to light aromatic hydrocarbons at a temperature within the range of 1800 to 2400 F. y i

Another object is to provide a process for the conversion of a gaseous hydrocarbon to light aromatic `hydrocarbonsfin selective and high yields, and into relatively minoramounts of valuable lay-product dioleflns. l

Other objects ofthis invention will be apparent. to one skilled in theart, from the accompanying discussion and disclosure. l

In accordance with a preferred embodiment of this invention, light aromatic hydrocarbons, such as benzene and toluene together with relatively minor amounts of other light aromatica, `and of diolefin hydrocarbons `such f as cyclopentadiene, butadiene, and others having from 4 to 6 carbon atoms per molecule, may be prepared in a novel two-stage process. A gaseous hydrocarbon is preheated under minimum cracking conditions, then further heated by admixture with combustion 'products` formedl by vburning hydrogen or a hydrogen-rich gas with oxygen, andthe resulting admixture isomaintained in a first stage at its existing highV temperature long enough for acetylene formation to take place, but short enough to substantially prevent undesirable dehydrogenationand/or polymerization of acetylene product. In ase'cond stage, the acetylenecontaining product is maintained in the presence `of hydrogen under conditions of temperature and `time favorable for the formation of desired light aromatic hydrocarbonproduct in high yield. It is a feature of my invention that light aromatic hydrocarbons are produced from an acetylene-containing gas in high" yield at high temperatures, withoutunduly hydrogenating .or dehydrogenating acetylene reactant,- whereby a more efficientv utilization of the'acetylene-containing Vmaterial is effected. Operating theA aromatichydrocarbon-forining step [in the presence of hydrogen at such `high.temperaturesl provides carbons, especially benzene, may be obtained;

Higher yields of. valuable diolefm hydrocarbon by-products are obtained, than heretofore.

Under the conditions of a preferred embodi` inent of my invention the arr'm'latic-forming.v

temperatures usually employed vary from 600 to I 51000" li'. above those usually used for conversion of acetylene stocks to light aromatichydrocarbons, and although they may favor some hydro-v genation of acetylene reactant to ethylene, which may be advantageous, they `areg above, those at I which any substantial rehydrogenation of acetyiene or ethylene to ethane will occur. The presence of hydrogen in the 'aromatics-forrning step inhibits undue dehydrogenation 'andpolymerization of acetylene reactants.. 1

Fresh hydrocarbon gas to be converted to the desired aromatic product is/preheatedin a pebble heater-type apparatus, Ywhich in ya preferred embodiment of my invention, usually comprises a series of substantially vertically-extending zones, often in vertical alignment with each other. Usually 'two such-zones.' are employed and are connectedbyla relatively vnarrow connecting zone,

or"throat.' The top or upper-zone is commonly Y referred-.to as the pebbleheating chamber and the? lowerv zonelas the gas 4reactonorl gas heatingV chamber. 'A7, combustion zone. or chamber, is positioned adjacent orin"closer-proximityto the sides of the lower portion of the heating chamber. Combustion gas from4 al combustion chamber is passed through ther-mass ofhpebbles inthe' pebble heating-chamber. Acontiguousmass of particulate contact material,often-referred toas pebbles, fills the pebble heating zone, theinterconnecting Zone -or throat, and the'gasvreactionaoreheating zone, and flows vdownwardly through these zones by gravity. Pebblesare discharged from the bottomof theV gas reaction zone-ata 4controlled rate, and returned, usually by elevatingmeans,- to the inle'tin the'upper portion of the pebble heating zonegf vA- contiguous movingv pebble lmass' thereby iills the p'elible'` heatingv zone,- gas heating zone, and the interconnecting zoneror vthroat -at all times. V Y' Thejterm pebbleias used in this specification denotes any-refractorymaterial influent form, size, and strength, which` will f flow readily by gravity through the various chambersof a pebble heater'apparatuse- Pebbles `are preferably,v sub'- stantially spherical and are about gli" to 1" in diameter, tol/2'7". Y Y

Inthe following' description, oney method of operating'my processwill be specically disclosed. The gures are diagrammatic illustrations oiJ apparatus in which my vprocess may -be practiced. It isto" be understood Vthatfthe Yflow diagram Vis diagrammatic only and-maybe altered in many respects, by those skilled in vthe art, and yet remain within themtended scope of my invention. 1 g

Referring then to Figure lgpebble heating zone I4 and eas heating zoneA II areginsulated chambers, eachcontaining a 'contiguous uentmass of pebbles 9 and connected by a heatV insulated conduit, forming pebble throat I6.' Conduitsf'l and 8 serve as pebble' inlet and'outlet for chambers i tand' l ,respectvelyf Star valve (or. other type of pebble feeder) i8 regulates'therate ofV flow the preferred range being about] 1/4 relationv with kpebble mass 9 in chamber I4'. Fuel gas, usually natural gas from line 6 and/or hydrogen recycle gas, from lines I3 and 65, described hereafter, lis introduced through line 22 and mixed with oxygen Yfrom line 2| to form a com-- bustion mixturel in line 23 which is vburned in com-- bustion Zonef20. Hot combustion gas formed in. zone `20 ascends through perforate support 25 at1 a temperature in the range of 2200 to 3500 F.. The temperature of thepebbles leaving zone I4,l i. e., enteringV zoneA lai.; is from.about.18,00.to'2800"' F. andV may lbe controlled toihigherl :or lower levels,y by regulating. theproporton *.fzoxygen introduced. through line- 211,? the proportionof :hydrogen rich;

gas introduced'zfrom1lines-.l.3:and-5.65;` and byreguef lation of the. rateiof pebblenflowthroughcham-1: ber It. Pebble; :temperatures-1mayrbedoweredt by introducing aninertigas diluenteto;the'ecom=v bustion chamber tozeffectreduction inametem perature.v Combustiongas thavin'gjmpartedi heat:-

to pebblesfin zonepM isv passed'zaseffluentfrom zone I 4 :through lines I Eandi I."I :torfurther: utili-l zation `not, shown, or: .through :lines ,I5 :and .IUIY asf;y described hereafter: :Methane .feed:.stock=, often; natural" gas,Y is introducedftuthrough :line-' Il! into the .lower portion.` of. gas.l heatingchamber .'I I.. entering at a pointv below perforate.gasadistribuetion plate 5,. and `is .passed :therethrough in direct: heat exchange relation .,withi, pebbles previously heated in zone ult; Yandfis.- heated :within:- fromf:.1'.

to .5 second toaaztemperaturewithimthesrangeas of 1800 to 240,09'E3amore preferable;temperature. range. being from 1900fto122009. F; zTh'ezfeXte'ntrof any hydrocarbon-:cracking 'inszone :IfI-Jis limited' by-thezshort contactrtim'e employed: I find usu ally th'atxI mayitolerateilasfmuchas 201 per cent cracking,V whenA preheatingfrmethane. in this 4man-`4 ner, f and I prefer-.in any case toV limit: theextent of *cracking-r by minimizing4v the' heating time.

gasv heating' chamber S-I I is passed throughy lineV i2-to a mixingT, orjVenturithroat, 36,"whe'rein` recycle gas from lines-,Z y Y preheater.- 21v to a temperature' usuallywithin the gas introduced -f-rom "line'' and'jthe'resulting admixture passed to combustioiirene33;v lIn some v cases preheating may-be unnecessaryandii'ydro-V directly to line "2 S through line Sil: 'I'he'hydrogem purityin the order'ofSO to iid-'per cent; in a'water cooledburner nozzlesandjin' 'a 'combustion cham# ber' dauetelyiil'imdvto withstand?ithe-requireu high temperatures" developed. Preferred con-f struction materials suitable for withstanding 'l'iighiH l.acciatezi `temperatures in the `process of my invention are discussed later with reference to Figure 2. Combustion gas from zone 33 comprises steam, usually in larger amounts, together with some car- =bon dioxide. Combustion gas temperatures are controlled to within the range of 3200 to 5000 F. Such control is effected by introducing an excess of hydrogen recycle gas from line 29 so that some unburned hydrogen is present in the combustion gas. For example, I prefer usually to form a combustion gas in zone 33 at a temperature of from 3600 to 4200 F. and in so doing I introduce from 100 to 250 per cent excess hydrogen recycle gas to the combustion step. Eluent combustion gas from zone 33 is passed through line 34, `usually at a temperature within the 3600 to 4200? F. range, into venturi`36 preferably at right angles to hot gases entering from line I2. Gases from lines l2 and 34 are passed into Vventuri 36 at linear velocities in the order of 100 to 400 feet per second. In passing through the Venturi throat the linear velocity of the gas admixture is accelerated to from 300 to 500 feet per second. The temperature of the gas passing from venturi 36 is regulated by the temperature vof the preheated gas from line l2 and temperature of combustion gas from line 34 and is within the limits of 2400 to 3500 F., although a more preferable temperature range is from 2600 to 3200D F. Eiiiuent gas from venturi 36 is maintained at the specific requisite temperature for a time within the limits of 0.001 to 0.05 second in reaction tube 31 attached to, or in close proximity to venturi 36. Acetylene is formed inreaction tube 31 in high yield, which yields may be attributed to the high temperature employed, and to a great extent to the presence of diluent gases from combustion zone 33, whereby undue degradation and/or hydrogenation of acetylene product is substantially prevented. The contact time of the reacting gas in zone 31 is necessarily short and is controlled,- by immediately quenching eiiiuent gas from zone' 31 to below a temperature at which undesirable by-products are formed. This is done byy passing eiiiuent from zone 31 intomixing T or venturi 38, usually of the sametype as venturi 36, and quickly quenching the acetylene product by admixing it therein with relatively cool hydrogen-rich recycle gas from line39, steam orwater spray from line 43 or flue gas from line` 44, or

any combination of any or all such gases entering through line 42. `Effluent gas from venturi 38 is passed from venturi 38at a temperature of about 1800 to 230091. Y

Operating in the manner described above, natural gas is quickly heated to a hightemperature necessary fortheV acetyleneforming reaction to proceed, is maintained at such conditions for the short Contact requisitefor lacetylene formation, and thereafter quickly quenched to terminate its retention at such conditions, whereby acetylene is selectively formed in high yield and can be utilized as such, in a subsequent aromaticsforming step.

Acetylene-containing gas is passed from venturi 38 to aromatics-forming step 41. wherein light aromatic hydrocarbons, such as benzene, are formed in` high yield together with relatively small amounts of diolefin hydrocarbons, and heavier aromatic hydrocarbons formed as byproduct. The reaction in zone 41 is conducted by maintaining gasestherein from venturi 38, at their existingtemperature for a duration of from 0.05 to 5.0 seconds. I'preferusually toI quench acetylene gas product inventuri 38 so that gas 6. fromyenturi 38 enters zone -41A at atemperature inthe range of 1900 to 2200 and under such conditions'a contact time within thek limits of 0.2fto 3.0 seconds may be selected. Eliiuent from zone` 41 is passed through line148 and quenched to a temperature in the range of about 400 to 800 F. by admixture in line 49 with water spray introduced through line-5 I. The resulting admixture is passed to wateriquenoh tower 51` through lines 55 and 56 wherein it iscontacted countercurrently with water introduced through lines 58 and 59, and cooled to a temperature usually within` the range of to 200 F. If desired, material in line 43 may first be passed through line 52, cooler ,53, and line 54to line 56, with or without water introduced through line 5l. Water may be drained from zone 51. through line 62, and any heavy by-product oils removed through line 6l. Product-containing gas is passed from zone, 51 through line 63 to angabsorber-stripper system. preferably of the conventional type employing a mineral seal `oil absorbent. Material in line 63 is introduced to absorber `64 and passed therein countercurrently in relation to downilowing fresh and/or stripped mineral seal oil introduced through line 1I. Hydrogen-rich gas is passed from an upper portion of absorber zone 64 through line 65 for combustion in zone 33 and/or zone 2U as already described, and/oras a quenching gas in venturi 33, already described. Any excess recycle gas in line 65 may be withdrawn through line B6. Enriched absorber` oil is passed through the lower portion of zone 64 through line I61 and introduced to stripper 68 maintained under distillation conditions whereby the rich oil is distilled and absorbed materials are liberated as vapors. Gaseous material is passed from stripper 68 to product separation means10 comprising coolers. separators, distillation equipment, storage tanks and the like not individually illustrated, which can be used to eifectv a separation of various selected product fractions. Lean absorber oil is passed from the lower portion of stripper 68 through lines 69 and 1l. Fresh absorber oil may be introduced to the absorber system through line 12. Selected product fractions Vinclude benzene withdrawn through line 13, toluene withdrawn through line 14,' cyclcpentadiene and other dioleiins withdrawn through line 16, and fraction containing light aromatic hydrocarbons such as styrene, methylstyrene, and xylenes, withdrawn through line 11. A relatively heavy fraction of aromatics comprising naphthalene and anthracene is withdrawn through line 18.

As already mentioned, the lining of the refractory `equipment is important in view of the high temperatures and high linear gas velocities utilized, employed as already discussed. The lining of combustion zone 33, lines l2 and 34, venturi 3,6, reaction tube 31 and venturi 38 is necessarily highly resistant to abrasive action, and. capable of withstanding the high temperatures of my process.

Preferred lining and insulating materials and the use of such materials in carrying out a preferred processor my invention are illustrated in Figure 2, which is a diagrammatic cross sectional view of the` system represented in Figure lj by lines l2 and 34, venturi 36, reaction tube 31 and venturi 38. Referring to Figure a, effluent line -I 2 is rigidly attached toventuri 36 by ange 8|.- Combustion zone 33 is rigidly attached to line 34-andventuri 36 by flange 82. Reaction tube 31 is rigidly attached to venturi 33 by Aharige 83 and toy venturi 38 by iiange 84.

l2 is lined with a`v dense', hard-burned, small-V grained,.h ighA purity, supported corundum lining 88 to resist abrasion and this llining 'is' backed up by alight weight insulating vmaterial 89, such as mullite or alumina. AOuter-jacket 9D maybe any suitable steel. Combustion chamber 33 is lined with zirconia 9|, partiallystabilized with CaO or Mg() and Vbacked -up by insulation '92 comprising zirconiaV and lightweight mullite or` alumina. Line 34 is ir'isulate'd in the same manner as combusticn chamber 33. `The liningof venturi 36 is also fabricated preferably 'of stabilized zirconia ed, but of a very small grain, dense, hard-burned structure to resist abrasive eiects 'of high.. gas velocities. zirconia refractory with la light weight insulating zirconia, 90. for temperatures of about 3000 F., and higher, orv below these temperatures with iight weight rnulliteV or insulating iire brick, not shown. Reaction tube 3l is preferably of the same vconstruction 'as vline I2 and may be backed with light weight valumina or` mullite insulating brick, and with the usual standard insulating materials when temperatures are lower than about 2600?' E'. Venturi 3B may be fabricated similarly to venturi Sii. Aromatics forming zone 4l is rigidly attached-itc venturi'38 lby iiange Bl and may be fabricated 'in'ahmanner similar to that of` reaction zone 3l@ 1.

For convenience'and clarity certain apparatus such as pumps, surge tanks, accumulators, valves, etc. have not been shown in the drawing. Obviously such inodicationsoi the present invention maybe practiced `without "departing from the scope of the invention. Y i

Asalready described,` a feature of my invention resides in the formationof aromatic hydrocarbons from acetylene at temperatures from 600 to l000 FQ above' those ordinarily employed, and the advantagesof this higher temperature opere ation'have already been pointed out. I am able to utilizefsuch high. aromatic forming` temperatures by operating in the lpresence of hydrogen. Under such conditions, 4,dehydrogenation of acetylene with consequent carbon formation, and hydrogenation of acetylene to ethane with consequent 4low yieldsof desired product is substantially prevented, and higher and ,more efficient conversions of acetylene are obtained. Some hydrogenation of acetylene to ethylene may occur, but if so, it is in no way disadvantageous. The temperature conditions are chosen such that partial hydrogenation tol ethylene is' possible and favorable, but atwhich total hydrogenation oi' acetylene to ethane or of any ethylene to ethane, is not promoted. The contact time is so: chosen that dehydrogenation of acetylene, and polymerination of acetylene isv kept at a minimum, and-so chosen that a minimum amount of unsaturates such as butadiene,`cyclopentadiene,:and Cs dienes areiormedtogether with highyields of light aromatic hydrocarbons particularly, benzene and toluene. yOnlyl .minor amounts ofheavier aromatic components-'tare andfthe like are formed at these'se'lctai temaeraiuesatacante@ times- Typical' pf .preferred time-temperature relation- `ships employed in the: practice roi. the 'aromatics It is preferable to backup the dense Y forming step of myinvention'are indicated as l follows:`

Time; Sec. Temp. F

1.5 mao 1,800

1.o mao 1,900

Iam not certain as to the exact mechanism of Vthe, reaction taking place in the arom-aticsforming step. However itis possible that, (1) acetylene is rstpartially hydrogenated to eth-A ylene as indicated bythe equation i v I CtHz-IHaC'zI-II 2) ethylene and acetylene vthen compolymerize .to form butadiene vas indicated by the ,equation and (3)', butadiene thus formed co-polymerizes with ethylene or acetylene followed by dehydrogenation andcyclization to benzene, as indicated bythe following equations In any case, some hydrogenation of acetylene to ethylene undoubtedly takes place under the conditions o1" my process and possibly contributes the high yields of benzene by virtue of its reaction with butadiene. Furthermore, the presence of any ethylene formed has a stabilizing effect upon the reactant gases and may contribute to maintaining the low carbon yields cb- 'tained Y The amount oi hydrogen present in the aromatics-forming step is -important in that it is advantageous that atleast 40 per cent of the gas in the aromatics-forming step consists of hydrogen. Usually the amount oihydrogen produced inthe acetylene-forming step is morethan that needed to supply 'the necessary hydrogen to the aromatics-forming step, and no hydrogen from any othersource is required. However, it is sometimesadvantageous to employ hydrogen as a Iquenching agent to coolgases entering the aromatic-forming zone, and .in such cases even larger amounts of hydrogen may be provided in the aromatios-iorming chamber. Usually I prefer vtoernploy some steam or water spray along with recycle hydrogen gas as a quenching agent. Hydrogen recyclegas is most advantageously employed 'asa quenching gas in those cases wherein the amount of hydrogen formed in the acetyleneforming step and passed to the aromatic forming step is` below that desired, as might be the case when heavier hydrocarbons comprise the stock feed to the acetylene forming step. I have' found thathydrogen may comprise as high as Aper cent of the gas in the aromatics :forming step and may be present in even higher concentrations, although excessively high' concentrations serve only to reducethe effectivecapacity of the chamber and auxiliary equipment.

Any gaseous hydrocarbon stock may be employed in the practice of my invention for conversion to acetylene. The process has a distinct advantage, in that meth-ane, or a methane-rich gas such as conventional dry natural gas, can be Yeconomically converted. The resulting acetyiene-rich productv is satisfactory in any Vcase for use inthe aromatic forming step.. Lower temperatures may begrequired for conversionof the heavier hydrocarbons to acetylene, but usually the 'conditions of the aromatic formingstep are substantially unchanged. V f

My; invention is inustrated by the following l example. The reactants, their proportions, and other `speciiic ingredients are presented as being typical and should not `be construed to limit the invention unduly. q

Example Natural gas of the following composition Volume Percent Component Eluent gas is discharged from the gas heating chamber at a linear velocity of 200 feet per second into a Venturi throat. In a separate combustion chamber, a hydrogen-rich recycle gas of the following composition,

Component ggg? Hi 84. 2 @H4 1.0 N3... 2. CO--- 2. 7 O3- 0. 1

produced in a subsequent purification step. is admixed in 150 per cent excess with oxygen of 95 per cent purity, and the resulting admixture burned to produce combustion gas, comprising carbon dioxide and steam, at a temperature of 4000 F.

Combustion gas at 4000 F. is discharged from the combustion chamber into the venturi at a linear velocity of 150 feet per second and is rapidly mixed therein with the preheated natural gas to form an admixture at a temperature of about 3000o F. The accelerated linear velocity of the gas mixture passing through the Venturi throat is about 300 feet per second. The resulting eiiluent gas admixture is maintained at its existing temperature of 3000" F. in a reaction tube, for a period of 0.01 second and under these i170 conditionspyrolysis occurs to produce a product gas ofthe following approximate composition:

Volume 1 Carbon and tar-free basis. .Y

lByweight. A The yield of acetylene per Si C. F. of natural gas r,feed 315` cubic. feet. vfice'tylene-containing productthus formedis rapidly quenchedby admixture in `a mixing 4'l'. or venturi with rela- `tivelyjcool hydrogen-containing gas, usually a hydrogen recyclestream already described, from a temperature, `of 2950 .F. to a temperature ,of 2100 F. and held.` at that temperature levelffor Va duration .of 0.8 second. Under such `conditions the acetylene containing gas is converted to a` crude aromatics product obtained in a yield of 1.0 gallon perM. S. C. F. of natural gas, containing about 70 per cent benzene, and 10per cent toluene With the remaining product cornprising cylopentadiene and other dioleiins in the .Ci tof Ctfrange together with other light aromatics such xylenes, styrene and methyl styrene, andfrelatively minor amounts of heavier aromatics predominantly naphthalene and anthracene.

Y As will be evident to those skilled in the art, various modications of this invention can be made, or followed, in the light of the: foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

I claim:

1. A process for the manufacture of an aromatichydrocarbon-containing product richinben- Zene and containing diolen hydrocarbons, comprising heating natural gas to a temperature in the range of from 1800 to 2400 F. for a time of from 0.1 to 0.5 second, admixing hydrogen with oxygen in regulated proportions and burning the resulting admixture to form combustion gas at a temperature within the range of 3200 to 5000 F., further heating said natural gas to a temperature Within the range of 2400 to 3500 F. by admixing same with hot combustion gas from said burning and maintaining the resulting admixture at said temperature for a time within the limits of 0.001 to 0.05 second, whereby an acetylene-containing product is formed, quenching said acetylene-containing product to a temperature Within the range of 1800 to 2300 F. by admixing same With cooler hydrogen, maintaining a concentration of hydrogen in the resulting quenched admixture of at least 40 volume per cent, and maintaining said resulting quenched product admixture at the last said temperature for a time of from 0.05 to 5.0 seconds whereby said aromatic containing product is formed, separating said product into selected fractions, and recovering said selected fractions as products of the process.

2. A process for the manufacture of an aromatic hydrocarbon-containing product rich in benzene and containing diolefin hydrocarbons having from 4 to 6 carbon atoms per molecule, toluene, xylenes, styrenes, naphthalenes and anihraeenes. vsaid ,presslcomprising heating natural gasto a 'temperature Within the range of 1800 to 2200 Ffwithin from 0.1 to 0.5 second,

admxing a regulated proportion of hydrogenrich gas described hereafter with oxygen and -burning Vthe resulting admixture to form combuston gas at a temperature within the range of 3600 to 4200 F., further heating said normally gaseous hydrocarbon to a temperature Within the limits 2000 to 3200 F. by admixing same with hot combustion gas from said burning, maintainrange of 1900 vto 2200o F. andmaintainingthe quenched. product et the `lastsad .temperature in Vthe presence, othydroeenin a Aconeentranon ef at least ,40 yolume :per cent for a duration 4'of from 0.2 to 3.0 secondsWherebygsad aromaticcontaining product is formed, Separating hydrogen-rich gas from said aromatic-containing product andrecycling a portion of same to said burning, recycling a. portion of` thehydrogenthus separatedas said .quench gasseparating a remaining portion of v said aromatic-containing product into selected aromatic hydrocarbon and diolen hydrocarbon fractions, and recovering said fractions as products of the process.

. 3. The process of claim 2 Whereinsaid quencl gas is supplemented with Water.

4. A process for the manuacture of an aromatic hydrocarboncontaining product rich in benzene and V containing dio1ef n hydro carbons, Corilrrsina vheating.a normally gaseous hydrocarbon to a. temperature `Within ,the limits of 1800to2 4 009 Fa burning hydrogen with oxygen to iform combustigmv gas at a temperature of at least 3200 F. and not higher"than5000, F., admixing normally gaseous hydrocarbon thus heateci-,With said ccmbustion gasin a proportion to 4form a resulting gaseous admixture at a temthe li1nit's,of0.05 to 5 seconds, Wherebya product rich-in aromatic hydrocarbons is formed,

Y separating a hydrogen-rich gas from said produ uct rich in aromatic hydrocarbons and recycling at least aportionofthe hydrogen thus separated v,as .said quench gas, andrecovering an aromatic hydrocarbonfraction as aproductof the process.

` 'SAMj P; ROBINSON.

REFERENCES CITED The following'references are of record inthe file of this patent: Y

UNITED STATES PATENTS 

2. A PROCESS FOR THE MANUFACTURE OF AN AROMATIC HYDROCARBON-CONTAINING PRODUCT RICH IN BENZENE AND CONTAINING DIOLEFIN HYDROCARBONS HAVING FROM 4 TO 6 CARBON ATOMS PER MOLECULE, TOLUENE, XYLENE, STYRENE, NAPHTHATENE AND ANTHRACENES, SAID PROCESS COMPRISING HEATING NATURAL GAS TO A TEMPERATURE WITHIN THE RANGE OF 1800 TO 2200* F. WITHIN FROM 0.1 TO 0.5 SECOND, ADMIXING A REGULATED PROPORTION OF HYDROGENRICH GAS DESCRIBED HEREAFTER WITH OXYGEN AND BURNING THE RESULTING ADMIXTURE TO FORM COMBUSTION GAS AT A TEMPERATURE WITHIN THE RANGE OF 3600 TO 4200* F., FURTHER HEATING SAID NORMALLY GASEOUS HYDROCARBON TO A TEMPERATURE WITHIN THE LIMITS 2600 TO 3200* F. BY ADMIXING SAME WITH HOT COMBUSTION GAS FROM SAID BURNING, MAINTAINING THE RESULTING ADMIXTURE AT SAID TEMPERATURE FOR A TIME OF FROM 0.001 TO 0.020 SECOND WHEREBY AN ACETYLENE-CONTAIING PRODUCT IS FORMED TOGETHER WITH BY-PRODUCT HYDROGEN, QUENCHING SAID ACETYLENE-CONTAINING PRODUCT IN DIRECT HEAT EXCHANE RELATION WITH A COOLER QUENCH GAS DESCRIBED HEREAFTER TO A TEMPERATURE WITHIN THE RANGE OF 1900 TO 2200* F. AND MAINTIANING THE QUENCHED PRODUCT AT THE LAST SAID TEMPERATURE IN THE PRESENCE OF HYDROGEN IN A CONCENTRATION OF AT LEAST 40 VOLUME PER CENT FOR A DURATION OF FROM 0.2 TO 3.0 SECONDS WHEREBY SAID AROMATICCONTAINING PRODUCT IS FORMED, SEPARATING HYDROGEN-RICH GAS FROM SIAD AROMATIC-CONTAINING PRODUCT AND RECYCLING A PORTION OF SAME TO SAID BURNING, RECYCLING A PORTION OF THE HYDROGEN THUS SEPARATED AS SAID QUENCH GAS, SEPARATING A REMAINING PORTION OF SAID AROMATIC-CONTAINING PRODUCT INTO SELECTED AROMATIC HYDROCARBON AND DIOLEFIN HYDROCARBON FRACTIONS, AND RECOVERING SAID FRACTIONS AS PRODUCTS OF THE PROCESS. 